Portable computer having a sealed hinge clutch

ABSTRACT

A portable computer including two plastic enclosures has a first hinge body attached to a first one of the enclosures. The first hinge body includes a bore formed therein. A flowable lubricant such as grease is disposed within the bore. A second hinge body is attached to a second one of the enclosures. The second hinge body includes an elongated shaft pivotally mounted within the bore having grooves formed on an outer surface of the shaft. A sealing member such as an O-ring is resiliently compressed between one of the grooves and an inner surface of the bore. A friction member is seated in another one of the grooves and in contact with the inner surface of the bore. The seal member has a coefficient of friction such that friction between the seal member and the bore is negligible with respect to friction between the friction member and the bore. The seal member limits the escape of lubricant and the resulting lubricant-induced stress cracks.

BACKGROUND

[0001] The disclosures herein relate generally to computer systems andmore particularly to portable computers having a sealed hinge clutch.

[0002] Portable computers typically include top and base enclosuresformed of synthetic, i.e. plastic material. The top and base of mostportable computers are attached using a metal hinge clutch to controlthe torque required to open and close the top. Most portable computersutilize a hinge clutch having either a friction plate design or afriction shaft design. The friction shaft design is often used tominimize the front-to-back dimension of the portable computer. For thistype of design, lubrication is necessary to maintain a uniform andconsistent pivoting action and clutch torque.

[0003] Various hinge devices have been used in computer housings. U.S.Pat. No. 5,566,048 discloses a hinge assembly that allows a displayhousing to pivot relative to a portable computer base. The hingeassembly has a pivot shaft attached to the display housing and a spring.The spring has two ends. One end is attached to the display housing, andthe other end is attached to the base. The spring counteracts the torquecreated by the weight of the display housing. This allows a smaller andlighter friction mechanism to be used to allow the display housing toremain in an open position at an angular orientation selected by theuser.

[0004] U.S. Pat. No. 5,142,738 discloses a hinge device used between arotatable component and a stationary component to work as a pivotingdevice. The device provides a restrained rotation of one component inrelation to the other. The rotational restraint is provided by a highviscosity grease and the torsional force of a coil spring insertedtherein in a predetermined angular range to restrain the rotating speedby means of the high viscosity grease and the coil spring.

[0005] U.S. Pat. No. 5,001,659 discloses a structure for connecting acover of a portable laptop personal computer, word processor or similarequipment having a display rotatably connected to a case whichaccommodates a body of the computer or word processor. The case andcover are electrically interconnected at co-active hinge portionsthereof by a pair of deformed O-rings and a pair of flat O-rings.

[0006] U.S. Pat. No. 4,730,364 discloses a hinge such as may be used forpivotally attaching a liquid crystal display panel to a portablecomputer base. The panel is held open in selected angular positions bymeans of a frictional fit between an O-ring and the end of a bearingwhich is rotatably retained within a follower, to compress the O-ringbetween it and the follower such that the frictional resistance betweenthe bearing and the follower may be adjusted to control the holdingforce on the panel.

[0007] Prior hinge clutches do not incorporate a reliable sealingmechanism to contain lubricant within the hinge clutch assembly. As aresult, over time, the lubricant has a tendency to migrate from themetal hinge clutch to the plastic housing. Most of the commonly usedlubricants deteriorate engineering grade plastics commonly used incomputer housings, making them more susceptible to stress cracks.

[0008] The loss of lubrication also causes the hinge torque to increasesignificantly. As the torque required to open and close the computerenclosure increases, the torque loading applied to the adjacent portionsof the enclosure also increases. The repeated opening and closing of topof the computer often result in the formation of stress cracks indeteriorated portions of the plastic enclosure.

[0009] Accordingly, there is a need for a lubricated hinge clutch thatovercomes the shortcomings of prior hinge clutch assemblies so as toavoid contaminating the plastic housing.

SUMMARY

[0010] One embodiment, accordingly, provides a hinge clutch having aseal for containing lubricant therein. To this end, one embodimentprovides a hinge assembly including a first hinge body having a boreformed therein and a second hinge body including an elongated shaftpivotally mounted within the bore. The shaft has a plurality of groovesformed therein. At least one of the grooves includes a friction membermounted therein and another of the grooves includes a seal membermounted therein. The seal member and friction member are in frictioncontact with the bore. The seal member has a coefficient of frictionsuch that friction between the seal member and the bore is negligiblewith respect to friction between the friction member and the bore.

[0011] A principal advantage is that the lubricant is sealed and limitedto the metal hinge so that portions of the plastic enclosure adjacent tothe hinge clutch assembly are not exposed to significant amounts oflubricant, thus reducing the potential for degradation of the plasticenclosure and the formation of stress cracks.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

[0012]FIG. 1 is a perspective view illustrating an embodiment of aportable computer with the top in a closed position.

[0013]FIG. 2 is a fragmented front view illustrating an embodiment of aportable computer with the top in an open position.

[0014]FIG. 3 is an exploded view illustrating an embodiment of a hingeclutch.

[0015]FIG. 4 is a cross sectional view taken along line 4-4 in FIG. 2.

[0016]FIG. 5 is a block diagram illustrating an embodiment of a computersystem.

DETAILED DESCRIPTION

[0017] An embodiment of a portable computer 10 is illustrated in FIGS. 1and 2. The portable computer 10 includes a base 12 and a top 14. Thebase 12 and the top 14 are pivotally attached by one or more hingeclutch assemblies 16, FIGS. 1 and 2. The top 14 is movable between aclosed position C, FIG. 1, and an open position 0, FIG. 2. The base 12and top 14 may be made from an engineering grade plastic such aspolycarbonate, acrylonitrile butadiene styrene (commonly known as ABS)or a combination thereof using a process such as injection molding.

[0018] The hinge clutch assembly 16 provides a resistive torque as thetop 14 of the portable computer 10 is being moved between the openposition O and the closed position C. The resistive torque provides theoperator of the portable computer 10 with resistive yet smooth feedbackwhile positioning the top 14 in a desired open position. The hingeclutch assembly 16 also provides suitable static friction to maintainthe top 14 in the desired open position.

[0019] Referring now to FIGS. 3 and 4, the hinge clutch assembly 16includes a first hinge body 18 and a second hinge body 20. The firsthinge body 18 includes a mounting flange 22 for attachment to the base12 of the portable computer 10. The second hinge body 20 includes amounting flange 24 for attachment to the top 14 of the portable computer10. The orientation of the hinge clutch assembly 16 may be reversedwhereby the first hinge body 18 is attached to the top 14 and the secondhinge body 20 is attached to the base 12. The mounting flanges 22, 24each include one or more holes 25 for facilitating attachment of therespective hinge body 18, 20 to the base 12 or top 14 of the portablecomputer 10.

[0020] Still referring to FIGS. 3 and 4, the first hinge body 18includes a tube portion 26 having a closed end 26 a adjacent to themounting flange 22 and an open end 26 b opposite the mounting flange 22.The tube portion 26 has a generally cylindrical interior surface 30,FIG. 3, defining a bore 27 having a diameter 31. The second hinge body20 includes a shaft 32 attached to the mounting flange 24. The shaft 32has a diameter 35, FIG. 4, and includes a plurality of grooves 34. Afriction band 36, FIG. 4, is received in each groove 34. The frictionbands 36 are ring-shaped pieces of wire such as a low carbon steel.

[0021] The difference between the diameter 31 and the diameter 35defines a friction band gap. The friction bands 36 are sized to have adiameter that is approximately the same or slightly larger than thefriction band gap. The friction bands are compressed between the tubeportion 26 of the first hinge body 18 and the shaft 32 of the secondhinge body 20. The compression of the friction bands 36 results infriction when the hinge bodies are pivoted with respect to each other.The friction provides the resistive torque applied by the hinge clutchassembly 16 during movement of the top 14 between the open position Oand closed position C.

[0022] It is desirable for the resistive torque to be maintained at arelatively constant level over the life of the hinge clutch assembly 16.Accordingly, a lubricant 38, FIG. 4, such as a flowable greasecomposition is disposed between the tube portion 26 of the first hingebody 18 and the shaft 32 of the second hinge body 20. A suitablelubricant has been found to be a product sold by the Dow Company underthe tradename Molycote. A key aspect of this invention is to minimizethe migration of the lubricant 38 from within the hinge clutch assembly16. Accordingly, a seal is formed between the tube portion 26 of thefirst hinge body 18 and the shaft 32 of the second hinge body 20. Oneembodiment for providing a seal includes forming a groove 40, FIG. 4, onan outer surface in the shaft 32 adjacent to the flange 24 andcompressing a resilient sealing member 42 between the groove 40 and theinterior surface 30 of the tube portion 26. A suitable resilient sealingmember 42 has been found to be a commercially available O-ring formed ofa material such as silicone rubber using a process such as injectionmolding. It is preferred that the O-ring be made of a material having alow coefficient of friction such that the friction associated with theO-ring is negligible with respect to that associated with thefriction-rings 36.

[0023] An embodiment of a computer system 50 is illustrated in FIG. 5.The computer system 50 includes at least one microprocessor 52. Themicroprocessor 52 is connected to a bus 54. The bus 54 serves as aconnection between the microprocessor 52 and other components of thecomputer system 50. One or more input devices 56 may be coupled to themicroprocessor 52 to provide input to the microprocessor 52. Examples ofinput devices include keyboards, touchscreens, and pointing devices suchas a mouse, a trackball and a trackpad. The computer system 50 may alsoinclude a display 58 which is coupled to the microprocessor 52 typicallyby a video controller 60. Programs and data are stored on a mass storagedevice 62 which is coupled to the microprocessor 52. Mass storagedevices include components such as hard disks, optical disks,magneto-optical drives, floppy drives, and the like. A system memory 64provides the microprocessor 52 with fast storage to facilitate executionof computer programs by the microprocessor 52. A peripheral device 66may be connected to the microprocessor 52 for providing the computersystem 50 with additional functionality. Examples of peripheral devicesinclude floppy disk drives, hard disk drives, compact disc players,digital video disc players, memory card readers, and other types ofdevices. The various components of the computer system are typicallymounted in a chassis or in an enclosure of a desktop or portablecomputer 10. It should be understood that other busses and intermediatecircuits can be employed between the components described above andmicroprocessor 52 to facilitate interconnection between the componentsand the microprocessor 52.

[0024] As it can be seen, the embodiments presented herein provideseveral advantages. Only a negligible amount, if any, of the lubricantcan escape from the hinge clutch. The potential for lubricant-inducedstress cracks in a plastic enclosure is reduced. The modifications tothe hinge clutch for implementing a seal do not necessitatemodifications to the enclosure or other portions of the computer.Furthermore, these modifications do not add significantly to the cost ofthe hinge clutch. The addition of the sealing member does not adverselyaffect the torque specifications of the hinge clutch. The torquespecification is maintained over a longer period of time as a result ofthe volume of lubricant in the hinge clutch remaining at a relativelyconstant level.

[0025] Although illustrative embodiments have been shown and described,a wide range of modification, change and substitution is contemplated inthe foregoing disclosure and in some instances, some features of theembodiments may be employed without a corresponding use of otherfeatures. Accordingly, it is appropriate that the appended claims beconstrued broadly and in a manner consistent with the scope of theembodiments disclosed herein.

What is claimed is:
 1. A hinge assembly, comprising: a first hinge bodyincluding a bore formed therein; a second hinge body including anelongated shaft pivotally mounted within the bore; and the shaft havinga plurality of grooves formed therein, at least one of the grooveshaving a friction member mounted therein, and another of the grooveshaving a resilient seal member mounted therein, the seal member and thefriction member being in friction contact with the bore, and the sealmember having a coefficient of friction such that friction between theseal member and the bore is negligible with respect to friction betweenthe friction member and the bore.
 2. The hinge assembly of claim 1further comprising a lubricant disposed within the bore of the firsthinge body.
 3. The hinge assembly of claim 1 wherein the lubricant isgrease.
 4. The hinge assembly of claim 1 wherein the lubricant is aflowable material.
 5. The hinge assembly of claim 1 wherein the sealmember is an O-ring.
 6. The hinge assembly of claim 1 wherein thegrooves are formed on an outer surface of the shaft.
 7. The hingeassembly of claim 1 wherein the first hinge body includes a tube portionhaving a closed end and an open end, the bore extending along alongitudinal axis of the tube portion and wherein the seal member ispositioned adjacent to the open end of the bore.
 8. The hinge assemblyof claim 7 wherein the friction member is positioned between the sealmember and the closed end of the tube portion.
 9. The hinge assembly ofclaim 8 wherein the friction member is formed of a low carbon steel. 10.A portable computer hinge assembly, comprising: a base; a top pivotallyconnected to the base by at least one hinge; a generally cylindricaltube portion of the hinge, the tube portion having an open end, a closedend, and an inner surface; a shaft of the hinge having a first end, asecond end and an outer surface, the shaft being pivotally mountedwithin the tube, the first end of the shaft being positioned adjacent tothe closed end of the tube and the second end of the shaft beingpositioned adjacent to the open end of the tube; a plurality of groovesformed on an outer surface of the shaft, at least one of the grooveshaving a friction member mounted therein, and another of the grooveshaving a resilient seal member mounted therein; and the resilient sealmember and the friction member being in friction contact with the tube,and the seal member having a coefficient of friction such that frictionbetween the seal member and the tube is negligible with respect tofriction between the friction member and the tube.
 11. A computer systemcomprising: a chassis including a base and a top connected to the baseby at least one hinge; a microprocessor mounted in the chassis; an inputcoupled to provide input into the microprocessor; a mass storage coupledto the microprocessor; a display coupled to the microprocessor by avideo controller; a memory coupled to provide storage to facilitateexecution of computer programs by the microprocessor; the hingeincluding a first hinge body having a bore formed therein; a secondhinge body including an elongated shaft pivotally mounted in the bore;and the shaft having a plurality of grooves formed therein, at least oneof the grooves having a friction member mounted therein, and another ofthe grooves having a resilient seal member mounted therein, the sealmember and the friction member being in friction contact with the bore,and the seal member having a coefficient of friction such that frictionbetween the seal member and the bore is negligible with respect tofriction between the friction member and the bore.
 12. The computer ofclaim 11 wherein the base and the top are formed of a polymericmaterial.
 13. The computer of claim 12 further comprising a lubricantdisposed within the bore of the first hinge body.
 14. The computer ofclaim 11 wherein the seal member is an O-ring.
 15. The computer of claim11 wherein the grooves are formed on an outer surface of the shaft. 16.The computer of claim 11 wherein the first hinge body member includes atube portion having a closed end and an open end, the bore extendingalong a longitudinal axis of the tube portion, and wherein the sealmember is positioned adjacent to the open end of the bore.
 17. Thecomputer of claim 16 wherein the friction member is positioned betweenthe seal member and the closed end of the tube portion.
 18. The computerof claim 17 wherein the friction member is formed of a low carbon steel.19. A method of limiting the migration of a lubricant from within ahinge assembly of a computer, comprising the steps of: forming a bore ina first hinge body; dispensing a prescribed quantity of the lubricantinto the bore; forming a plurality of grooves on an outer surface of ashaft of a second hinge body; mounting a seal member in one of thegrooves; mounting a friction member in another one of the grooves;inserting the shaft into the bore of the second hinge body whereby theseal member is resiliently compressed between the groove and an innersurface of the bore; and engaging the seal member and the frictionmember in friction contact with the bore, the seal member having acoefficient of friction such that friction between the seal member andthe bore is negligible with respect to friction between the frictionmember and the bore.
 20. The method as defined in claim 19 wherein thestep of mounting the friction member includes the step of mounting aplurality of friction members in a plurality of the grooves.